Synchronous amplitude and time control for an optimum dynamic range variable photonic delay line

    Authors

    N. A. Riza;N. Madamopoulos

    Comments

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    Abbreviated Journal Title

    Appl. Optics

    Keywords

    PHASED-ARRAY ANTENNA; MICROWAVE SIGNAL ATTENUATOR; OPTICAL ANALOG LINK; EXTERNAL MODULATION; FIBEROPTIC LINKS; SYSTEMS; Optics

    Abstract

    A synchronous-amplitude-controlled and time-delay-controlled photonic controller for phased-array antenna applications is proposed and demonstrated. Amplitude control is based on a variable optical attenuator system that operates in synchronism with the photonic delay line (PDL). This amplitude control system can provide both the signal calibration for the different PDL channels and settings required for driving the antenna elements of a phased-array radar and the optimum optical power levels that impinge on the photodetector for optimum fiber-optic-link performance. Various variable amplitude control modules based on ferroelectric liquid crystals, polymer-dispersed liquid crystals, and photoconductive devices are proposed. We show that the dynamic range loss due to a switched-PDL inherent structure loss can be compensated when we control the optical power from the laser, using the synchronous optical attenuation system. For the first time to our knowledge, full dynamic range loss compensation is demonstrated for an external-modulation-fed 3-bit switched PDL with a structure optical insertion loss of 5.5 dB. A compression dynamic range of 158 dB.Hz was measured at 6 GHz, and a spurious free dynamic range of 111 dB.Hz(2/3) was estimated. Feasibility of the dynamic range compensation technique for multichannel, higher-insertion-loss PDL systems is discussed. (C) 1999 Optical Society of America.

    Journal Title

    Applied Optics

    Volume

    38

    Issue/Number

    11

    Publication Date

    1-1-1999

    Document Type

    Article

    Language

    English

    First Page

    2309

    Last Page

    2318

    WOS Identifier

    WOS:000079638900021

    ISSN

    1559-128X

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